Linear motor and electric injection molding machine using the same

Abstract

An electric injection molding machine comprises a barrel which holds a screw therein, a voice coil type linear motor which moves the screw in the axial direction thereof. The linear motor has a coil, a yoke extending along the coil, and a magnet movable relatively to the coil in the axial direction thereof. The injection molding machine comprises a coolant passage in the yoke and a cooling device for cooling the coil. Temperature related to the coil or a coolant is detected, and the coolant is control in accordance with the detected temperature.

What is claimed is:  
     
         1 . A voice coil type linear motor comprising: 
 a cylindrical coil for magnetic field generation;    a yoke extending along the coil;    a magnet movable relatively to the coil in the axial direction thereof; and    cooling means which cools the coil.    
     
     
         2 . An electric injection molding machine comprising: 
 a barrel which holds a screw therein; and    a drive section having a linear motor for use as a drive source which moves the screw in the axial direction thereof;    the linear motor being a voice coil type linear motor comprising a cylindrical coil for magnetic field generation, a yoke extending along the coil, a magnet movable relatively to the coil in the axial direction thereof, and cooling means which cools the coil.    
     
     
         3 . An electric injection molding machine according to  claim 2 , further comprising a temperature sensor, which detects temperature related to the coil or a coolant of the cooling means, and a control device which controls the coolant in accordance with the temperature detected by the temperature sensor.  
     
     
         4 . An electric injection molding machine according to  claim 2 , wherein the magnet is provided with a cooling jacket through which the coolant circulates.  
     
     
         5 . An electric injection molding machine according to  claim 3 , wherein the magnet is provided with a cooling jacket through which the coolant circulates.  
     
     
         6 . A voice coil type linear motor according to  claim 1 , wherein the cooling means is an electronic cooling device having Peltier elements.  
     
     
         7 . An electric injection molding machine according to  claim 2 , wherein the cooling means is an electronic cooling device having Peltier elements.